2002 Legacy B4

I recently imported a 2002 Subaru Legacy B4 and it came with a blown 100A main fuse. I replaced with a generic fuse but seems like there is a power problem which may be causing injector and cam position sensor throwing a check light for a few seconds when i run an accessories such as power windows. The check light does not stay on but just flickers for a few seconds and disappears The problem is worse at night when i switch on the lights as it causes the accelerator not to respond for a few seconds as the car refuses to take off and then the car takes off with normal power. In the afternoon without the lights it drives fine and is powerful but the problem now is that the fuel consumption is now pretty high. I do not know if it is related but the fog lights also are not working